High photocatalytic and photo-Fenton-like activities of ZnO–reduced graphene oxide nanocomposites in the degradation of malachite green in water

ZnO-reduced graphene oxide (rGO) nanocomposites with rGO/ZnO mass ratio of 0-0.20 were synthesised by a hydrothermal method. The photodegradation experiments of malachite green in water on the nanocomposites indicated that the photodegradation rate increased with increasing rGO content and initial solution pH. Significantly, the Fenton-like photodegradation of the malachite green in water was observed in the presence of H₂O₂. This Fenton-like reaction speeds up as the rGO/ZnO ratio increases. The quasi-kinetic rate constants of the photocatalysis systems are in the range of ~0.0064-0.0247 min^-1 and increase about one magnitude to ~0.0868-0.2120 min^-1 by the Fenton-like reaction.